The StageBug SB-4 Piezo DI from Radial Engineering is a compact active direct box that has been optimized for use with piezo transducers. This enables violin, dobro, mandolin, cello, upright bass, and other instruments that are best amplified using a piezo to be connected to a mixing board or recording device.

This unit features a 1/4" input for the instrument pickup and a 10 MΩ impedance that smoothes out troublesome peaks. The higher impedance also broadens the frequency response for a more natural and pleasing sound. The active circuit performs the high-to-low impedance conversion and balances the signal to enable long runs upwards to 328’ (100m) without loss, delivering linearity and low distortion throughout the audio range.

To help eliminate feedback on stage, it is equipped with a high-pass filter and 180° polarity reverse switch. The high pass filter eliminates excessive bottom end, which in turn reduces resonance that can cause the top of the instrument to vibrate. The 180° polarity reverse helps reduce acoustic hot spots on stage by changing the phase relationship between the PA system and room acoustics, which can combine at certain frequencies to create peaks. Reversing the polarity eliminates the acoustic peak without resorting to severe equalization which only serves to compromise the natural tone of the instrument. The unit’s connections include an AUX out for a stage amplifier plus a standard XLR output to feed the PA. Power is derived from the console's 48V phantom, thus eliminating the need for batteries or external supply.

These features combined with the compact size makes this unit a suitable companion for orchestral artists, blue grass players, and pop string quartets that need to turn it up when in concert.